The present invention relates to a method of working a small recess portion utilized in fabricating a part of a liquid ejection head or the like and a method of fabricating a liquid ejection head and a liquid ejection head.
Forging is utilized in various product fields, for example, it is known that a pressure generating chamber of a liquid ejection head is formed by forging a metal material. The liquid ejection head is for ejecting a pressurized liquid from a nozzle opening as liquid drops and there is known a liquid ejection head constituting an object by various liquids. As a representative one among them, an ink jet recording head can be pointed out. Hence, an explanation will be given of a background art by taking an example of the ink jet recording head.
The ink jet type recording head (hereinafter, referred to as recording head) is provided with a plurality of a series of flow paths reaching nozzle openings from a common ink chamber via pressure generating chambers in correspondence with the nozzle openings. Further, in view of a request for small-sized formation, it is necessary to form the respective generating chambers by a fine pitch in correspondence with a recording density. Therefore, a wall thickness of a partition wall portion for partitioning the contiguous pressure generating chambers becomes extremely thin. Further, a flow path width of an ink supply port communicating the pressure generating chamber and the common ink chamber is further narrowed more than that of the pressure generating chamber in order to efficiently use an ink pressure in the pressure generating chamber for delivering ink drops.
Further, a nozzle plate formed with the nozzle opening is fabricated by a metal plate in view of a request for workability or the like. Further, a diaphragm portion for changing a volume of the pressure generating chamber is formed by an elastic plate. The elastic plate is constituted by a double structure of pasting a resin film onto a support plate made of a metal and is fabricated by removing a portion of the support plate in correspondence with the pressure generating chamber.
Patent Reference 1: JP-A-2004-98165
Meanwhile, according to the above-described recording head of the background art, the pressure generating chamber is constituted by a groove-like recess portion aligned at a pressure generating chamber forming plate made of a metal by pressing or the like. The groove-like recess portion is formed as a small recess portion, a width of the groove is very narrow, further, a wall thickness of a partition wall portion for partitioning the groove-like recess portions is extremely thin and therefore, utmost caution is paid in accurately providing a recess shape of the pressure generating chamber. Particularly, it is important for making volumes of the respective pressure generating chambers uniform to align end portions of the groove-like recess portions on an imaginary line having a predetermined shape. Since the groove-like recess portion is the very small recess portion as described above, a variation is generated in the shape of the groove-like recess portion by a flowing phenomenon of a metal material in working or other working conditions, and it seems that a problem is posed in the above-described aligned state on the imaginary line.